<html>

<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width">
    <title>css 菜单栏左右滑动</title>
    <style>
        .column {
            overflow: hidden;
        }

        .column-left {
            height: 400px;
            background-color: #fff;
            position: relative;
            float: left;
        }

        .column-right {
            height: 400px;
            padding: 16px;
            background-color: #eee;
            box-sizing: border-box;
            overflow: hidden;
        }

        .resize-save {
            position: absolute;
            top: 0;
            right: 5px;
            bottom: 0;
            left: 0;
            padding: 16px;
            overflow-x: hidden;
        }

        .resize-bar {
            width: 200px;
            height: inherit;
            resize: horizontal;
            cursor: ew-resize;
            opacity: 0;
            overflow: scroll;
        }

        /* 拖拽线 */
        .resize-line {
            position: absolute;
            right: 0;
            top: 0;
            bottom: 0;
            border-right: 2px solid #eee;
            border-left: 1px solid #bbb;
            pointer-events: none;
        }

        .resize-bar:hover~.resize-line,
        .resize-bar:active~.resize-line {
            border-left: 1px dashed skyblue;
        }

        .resize-bar::-webkit-scrollbar {
            width: 200px;
            height: inherit;
        }

        /* Firefox只有下面一小块区域可以拉伸 */
        @supports (-moz-user-select: none) {

            .resize-bar:hover~.resize-line,
            .resize-bar:active~.resize-line {
                border-left: 1px solid #bbb;
            }

            .resize-bar:hover~.resize-line::after,
            .resize-bar:active~.resize-line::after {
                content: '';
                position: absolute;
                width: 16px;
                height: 16px;
                bottom: 0;
                right: -8px;
                background: url(./resize.svg);
                background-size: 100% 100%;
            }
        }
    </style>
</head>

<body>
    <div class="column">
        <div class="column-left">
            <div class="resize-bar"></div>
            <div class="resize-line"></div>
            <div class="resize-save">
                左侧的内容，左侧的内容，左侧的内容，左侧的内容
            </div>
        </div>
        <div class="column-right">
            右侧的内容，右侧的内容，右侧的内容，右侧的内容
        </div>
    </div>
</body>

</html>